1. Field of the Invention
The invention disclosed herein generally relates to the field of composite materials. For the purposes of this patent disclosure the term “composite material(s)” may be taken to mean a mixture (on a macro scale) of two or more materials that are solid in a finished state, are mutually insoluble, and differ in chemical nature. Certain preferred composite materials for the practice of the herein described invention are those polymeric beads associated with each other through use of adhesive materials. Such polymeric bead/adhesive composite materials are often referred to as “foam” or “foamed” materials. The most preferred composite materials for the practice are those polymeric bead/adhesive composite materials wherein the polymeric bead component is comprised of beads that have been treated in an electrically excited field.
The polymeric bead/adhesive composite materials of this patent disclosure have a wide variety of uses. For example they can be used as construction materials, insulation materials, sound and/or vibration abatement materials, drainage control materials, waste pond and/or landfill covers, packaging materials, padding for sports gear and/or medical equipment that comes into contact with the human body (e.g., helmets, shoulder pads, prosthetic devices, mattresses, cushions, etc.), indeed virtually any application where foam materials are employed. This invention also relates to treating those polymer beads used to make composite materials so that they will better form the end product materials of this patent disclosure. Generally speaking these treatment processes involve treating polymer beads in an electrically excited field.
2. Discussion of the Background
Designing composite materials for a wide variety of purposes (exterior wall and/or roof insulation, building foundation drainage control systems, athletic field padding, e.g., to be placed under athletic field turf, sound and/or vibration absorbing materials, waste pond covers, protective padding sports equipment, prosthetic devices, mattresses, etc. presents numerous challenges. For example, composite materials used as insulation in wall or roof construction is most preferably air breathable in nature. Composite materials used in building foundation drainage systems must be water permeable (preferably in all three directions). Designing protective padding for impact absorbing athletic gear is especially challenging. In addition to having the padding perform its primary function of repeatedly absorbing high impact forces, such padding also should be lightweight, air breathable, water permeable and washable. It also should be easily integrated into sports gear such as jerseys, pants, helmets, shoulder pads and the like—in a manner that does not unduly inhibit the user's movements.
Thus, using athletic equipment design as an example of such design challenges, one would note that many prior art pads and padding techniques accomplish some of these goals—to varying degrees. For example, U.S. Pat. No. 4,343,047 to Lazowski teaches use of loosely filled, lightweight beads in a breathable casing to form a helmet pad. The helmet pad readily conforms to the contours of the wearer's head. In use, the loose beads are designed to move or shift around relative to each other within the casing. The beads also are designed to be crushable in order to absorb and attenuate particularly high impact forces. Crushable beads of this kind are designed to absorb one major impact, much like a car airbag. Therefore, padding made from crushable beads cannot be used in most athletic gear (e.g., football thigh and knee pads) since it must be able to withstand repeated impacts without losing its mechanical integrity.
Other prior art, sports-related, padding materials use incompressible beads that are designed not to be crushed (e.g., British Patent No. 1,378,494 to Bolton, U.S. Pat. No. 3,459,179 to Olesen, and U.S. Pat. No. 4,139,920 to Evans). Still others use beads that are resilient rather than crushable (e.g., U.S. Pat. No. 3,552,044 to Wiele and U.S. Pat. No. 5,079,787 to Pollman). These beads also are loosely packed in a bead containment sack or casing. Here again, this allows the beads to move, roll, flow, etc. relative to each other in order to achieve maximum pad conformation to the shape of a particular part of the human body. The Wiele patent further teaches lubrication of such beads to enhance their flowability to achieve such conformation. In this art, these loosely packed conditions are often referred to as “underfilling”. The general object of underfilling is to achieve a padding material having the flow and conforming characteristics of a liquid-filled pad, without the burden of carrying the relatively heavy weight of liquids—or the need for waterproofing the casings needed to contain them.
While underfilled pads initially behave like a liquid when subjected to impacts, they have a tendency toward allowing the beads contained therein to be permanently driven out of the way in localized areas that receive repeated blows. This tendency gradually reduces the thickness of the padding around the human body part receiving the repeated blows. Indeed, this tendency may even allow the human body part to eventually “bottom out” in the pad. Under such bottomed out conditions, the beads are driven away from the very areas where they are most needed.
Consequently, much of the padding used in today's athletic equipment is comprised of one or more sheets or layers of foam-like materials rather than underfilled pads. So used, these foam-like materials have the distinct advantage of not easily bottoming out. They also are relatively light in weight and inexpensive to manufacture. There are two general types of foam padding materials. The first type comprises so-called “closed cell” foams. Aside from not being inclined to bottom out, such foams also have the advantage of not absorbing moisture such as perspiration. However, closed-cell foams tend to be stiff—and, hence, body movement-stifling. Moreover, closed cell foam materials do not readily conform to human body contours, particularly under the rapidly changing conditions associated with many contact sports. Moreover, closed-cell foams do not “breathe” very well and therefore do not allow dissipation of the equipment user's body heat. Closed cell foams also suffer from the fact that they are not readily sewn into, or washable with, athletic clothing and equipment such as jerseys, pants and the like.
The second type of foam commonly used in sports and medical equipment comprises so-called “opened-cell” foams. These foams tend to be softer and more pliable than closed-cell foams. Hence, they tend to better conform to various contours of the human body, especially under rapidly changing conditions. They also do not inhibit the user's movements nearly as much as closed-cell foams. Open-cell foams also have good breathing qualities. Opened-cell foams do, however, tend to absorb and hold moisture and odor to such a degree that this tendency is often regarded as their major drawback. Hence, open-cell foams are usually coated with a waterproofing material (e.g., vinyl and the like) to prevent high levels of absorption of perspiration. Unfortunately, use of these coating materials tends to make athletic pads made from opened-cell foams considerably less breathable and, hence, more body heat-retaining. Use of these coating materials also tends to make the underlying pads less pliable.
Padding materials made from polystyrene, polyethylene and polypropylene have proven to be especially efficacious in athletic equipment (e.g., football helmets, shoulder pads, etc.) that must repeatedly absorb impacts. The precursor beads (polystyrene, polyethylene, polypropylene and mixtures thereof) from which these materials are made are simply placed in a container and subjected to heat treatments (e.g., steaming) in order to join the individual beads to each other and thereby create unified materials from which padding for sports equipment can be made. These manufacturing processes are very generally depicted in FIGS. 2-7 of this patent disclosure. For example, the cross-sectional bead array shown in FIG. 2 can be heated (e.g., by steam) in order to join or meld the individual beads 1, 2, 3, 4, 5, 6, etc. into a unified body of material such as that depicted in FIG. 3. In FIG. 2, the individual beads are shown having idealized, round configurations. This implies that void spaces will exist between abutting individual beads. Those skilled in this art will appreciate that these void spaces become filled in when the beads are made fluid or plastic in nature by the heat treatment used to join or meld the beads together in the manner suggested in FIG. 3. After such heat treatments, the composite body constitutes a “foam” from which padding materials can be made. A perspective view of a generalized block of such foam material is depicted in FIG. 4. It illustrates that the void spaces shown in FIG. 2 become filled in (in all three dimensions) by the material from which the individual beads are made; hence the resulting foam material does not possess particularly good breathing qualities.
Other composite materials, that are primarily used in applications other than athletic equipment (e.g., building materials such as those used in insulation slabs, sound/vibration absorbing slabs, athletic turf padding/drainage control slabs, building foundation drainage control slabs, waste pond covers, etc.), have been designed to maintain void spaces between their individual beads even after they have been subjected to such heat treatments. The void spaces contribute to the relatively light weight of such building materials. Such materials are usually made from hollow microspheres or microbeads that are—to some degree—covered with a resin material that is applied to the microspheres by melting the resin material in the presence of the beads. For example, U.S. Pat. No. 5,587,231 (“the '231 patent”) teaches a foam material made from a mixture of hollow ceramic microspheres and dry granules of a resin powder. The dry resin powder is a thermosetting or high-temperature thermoplastic whose individual particles are mechanically mixed into a mass of dry microspheres. Upon heating the hollow microsphere/resin mixture to the resin powder's melting point, the microspheres become bonded together by a cured form of the resin that results from the heat treatment and subsequent cooling of the melted resin material. That is to say that the resin is in a melted state when it first goes into a liquid state (by virtue of having been melted) and makes its initial contact with the beads in this liquid (and melted) state. The end product material is an array of (1) hollow ceramic microspheres, (2) a thermally set resin that interconnects individual microspheres and thereby serves to hold said microspheres in a cohesive body and (3) void spaces. Optionally, the material may contain fiber strands as well. These materials are depicted in FIGS. 2A and 2B of the '231 patent as well as in FIG. 12 of the present patent disclosure.
Because the dry resin powder taught in the '231 patent disclosure is simply mechanically mixed with the microspheres, the resulting materials are, to some degree, characterized by the fact that the cured resin does not tend to fully coat the microspheres (again see FIGS. 2A and 2B of the '231 patent or FIG. 12 of the present patent disclosure). That is to say that the '231 patent's thermally set resin material associates with the beads in such a manner that it generally serves to form branch-like, or net-like, components whose individual elements serve to interconnect the beads at certain limited locations on the bead's surface—as opposed to fully coating the microspheres. The '231 patent's end product materials also are characterized by the fact that the void spaces created by the thermal setting of the resin tend to be “clogged” and somewhat randomly created in said materials. Hence, the breathing qualities of these materials are not particularly good. This is, however, of little or no concern to the '231 patent disclosure because its light weight materials are intended for use as construction materials in buildings, aircraft, trucks, boats, tanks and the like. These breathing qualities will be contrasted with the padding materials of applicant's patent disclosure wherein the resulting bead/adhesive/void space materials remain highly breathable and hence better suited for use in athletic equipment or medical equipment.
U.S. Pat. No. 5,888,642 (“the '642 patent”) teaches a padding material similar to that taught in the '231 patent. It is comprised of microspheres that are held together in a coherent body by two resins. One of these resins is melted and subsequently thermally set. The teachings of this patent disclosure differ from those of the '231 patent in that the second resin in the '642 patent forms microballoons when suitably heated. In any case, the resulting material also has an array of hollow beads, resins and void spaces. It does not, however, necessarily have fiber strands as part of its make as in the case in the '231 patent. A representative material is shown in FIG. 9 of the '642 patent and in FIG. 11a of the present patent disclosure. As was the case in the '231 patent, the materials taught by the '642 patent are intended for use as construction materials rather than as padding for athletic equipment or medical equipment.
U.S. Pat. No. 3,640,787 to Heller teaches a method of making construction materials from fully coating shaped beads of low specific gravity (e.g., polystyrene) with a liquid binder material. In effect, the beads are first immersed in a liquid form of the binder. This immersion fully coats the beads. The resulting binder-covered beads are, in turn, coated with a solid pulverulent material such as particles of metal oxides, sand and the like. FIG. 4 of the Heller patent disclosure shows that cell-like bodies are formed from the beads (e.g., polystyrene beads) and that the walls of these cells are comprised of the hardened binder material which also contains the pulverulent materials embedded therein. Since the resulting honeycomb-like materials have no void spaces between its adjoining cells, the resulting material does not have good breathing qualities. In other words, Heller's individual cells do have void spaces, but they are totally surrounded by the cell walls created from the beads and binder/pulverant coating on those cell walls. Here again, however, this is of little concern to the Heller patent disclosure since its end product materials also appear to be intended for use as building construction materials rather than padding for athletic equipment.
Thus, there remains a continuing need for composite materials that are particularly characterized by the fact that they are highly breathable, water permeable (especially in all three directions) light in weight, conformable to the human body, and able to withstand repeated blows without mechanically breaking down and/or bottoming out. To this end, the composite materials disclosed herein have high levels of all of these desired qualities. Moreover, they can be easily incorporated into a wide variety of applications. They also are (if need be) washable and relatively easy, and inexpensive, to make.
It might also be noted that, even though their ability to repeatedly absorb blows may not be needed, the other attributes of these padding materials (breathability, light weight, conformability to the human body) also make them well suited for use in medically related devices such as prosthetic devices, cushions, mattresses and the like. Moreover, the breathing qualities of these materials may, alone, make them suitable for use as padding for certain goods that must be exposed to air during shipping. The breathability of these composite materials also makes them useful as filters. For example they would be particularly useful in equipment where both padding and filtering functions must be performed by the same material. By way of example only, applicant's materials can be used as padding in electrical equipment such as computer hard drive equipment that must be protected from mechanical disturbances and subjected to a stream of cooling air that must be filtered before introduced into hard drives that have very little tolerance for particles of foreign materials. There are of course many applications where “breathability” may not be a particularly important attribute—but does no harm in that application (building insulation, soundproofing, drainage control packaging, etc.).